Caulk, adhesive, potting material and other fluid systems are commonly contained in tubular or cylindrical cartridges of the type having a closure wall with an outlet nozzle at one end and an opposite open end that is closed by a wiper slidably seated against the inside face of the cartridge wall. Generally, the fluid system utilizes only a single component which is used directly as discharged from a single cartridge. Multiple component material systems also exist and are formed by blending different components together in precise ratios just before the intended end use of the composite material.
Most contained fluid materials are substantially incompressible and many have poor flow characteristics and/or high viscosities. The material is discharged from the outlet nozzle by increasing the static pressures of the material within the cartridge sufficiently to overcome all back pressures against such flow. A restricted flexible tubing or the like commonly is connected over the outlet nozzle for improving flow control, such as for directing the material into narrow cracks or cavities, further increasing the needed static discharge pressures. The static pressures should be maintained substantially uniform in order to provide a consistent material discharge.
Dispensing tools are available to force a plunger axially of and into the open cartridge end and against the wiper, for generating the static pressures needed to discharge the contained material from the cartridge. Such dispensing tools conventionally utilize a rod connected to the plunger and a power device, activated by a control such as a trigger, that forces the rod and its plunger axially through the cartridge. Such dispensing tools generally are powered pneumatically, or manually such as by some type of manual ratchet mechanism indexed incrementally upon each trigger squeeze. High ratio manual ratchet mechanisms are available to generate most needed plunger forces and static material pressures.
High static pressures however promote material leakage past the wiper and out the open rear cartridge end. Leakage is messy and potentially damaging to the surroundings or tool user. Moreover, leakage of a multiple component material system could modify the desired component ratios, possibly adversely changing the expected physical properties of the resulting material.
Existing multiple component dispensing tools commonly hold the separate cartridges in adjacent side-by-side relationship, and advance separate plungers in unison through the respective cartridges. A mixing tube is connected over the separate cartridge nozzles, for blending the components together throughly before being discharged as the intended material from a single nozzle. Higher static pressures are required for this blending action. Large cartridge diameters can be used to provide for adequate volumetric capacity and/or specific component ratios, again with resulting increased plunger forces. The drive rod commonly is offset from a plane extended through the spaced multiple component plunger rods, creating an offset couple between the strained drive and plunger rods. Consequently, during even normal tool operation, forces tend to deform the tool and/or twist the wiper out of square with its cartridge walls, further inducing material leakage.
Existing material suppliers use cartridges of different and frequently incompatible designs, whereby a dispensing for one supplier's cartridges cannot accommodate the cartridges of other suppliers. Thus, a tradesman user may need different dispensing tools on hand in order to use the material cartridges provided for a specific job.
Common multiple component materials include two-part epoxies, urethanes, silicones, phenolics, acrylics and polyesters. One successful use of a multiple component material has been filling surface cracks in concrete structures to restore its structural integrity.
Our copending patent application having Ser. No. 07/882,836 filed May 14, 1992, now U.S. Pat. No. 5,263,614, patented Nov. 23, 1993, discloses related manual dispensing tools of the type having a spring linkage between the actuated power device and driven plunger, suited for storing and dissipating unused energy inputted to the power device for maintaining substantially continuous dispensing static pressures on the component material, such as even between successive trigger squeezes.